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ERR(3) DragonFly Library Functions Manual ERR(3)

NAME

ERR - OpenSSL error codes

SYNOPSIS

#include<openssl/err.h>

DESCRIPTION

When a call to the OpenSSL library fails, this is usually signaled by the
return value, and an error code is stored in an error queue associated
with the current thread. The ERR library provides functions to obtain
these error codes and textual error messages. The ERR_get_error(3)
manpage describes how to access error codes.
Error codes contain information about where the error occurred, and what
went wrong. ERR_GET_LIB(3) describes how to extract this information. A
method to obtain human-readable error messages is described in
ERR_error_string(3).
ERR_clear_error(3) can be used to clear the error queue.
Note that ERR_remove_state(3) should be used to avoid memory leaks when
threads are terminated.

ADDING NEW ERROR CODES TO OPENSSL

See ERR_put_error(3) if you want to record error codes in the OpenSSL
error system from within your application.
The remainder of this section is of interest only if you want to add new
error codes to OpenSSL or add error codes from external libraries.
When you are using new function or reason codes, run makeerrors. The
necessary #defines will then automatically be added to the sub-library's
header file.
Addingnewlibraries
When adding a new sub-library to OpenSSL, assign it a library number
ERR_LIB_XXX, define a macro XXXerr() (both in <openssl/err.h>), add its
name to ERR_str_libraries[] (in /usr/src/lib/libcrypto/err/err.c), and
add ERR_load_XXX_strings() to the ERR_load_crypto_strings() function (in
/usr/src/lib/libcrypto/err/err_all.c). Finally, add an entry
L XXX xxx.h xxx_err.c
to /usr/src/lib/libcrypto/err/openssl.ec, and add xxx_err.c to the
Makefile. Running makeerrors will then generate a file xxx_err.c, and
add all error codes used in the library to xxx.h.
Additionally the library include file must have a certain form.
Typically it will initially look like this:
#ifndef HEADER_XXX_H
#define HEADER_XXX_H
#ifdef __cplusplus
extern "C" {
#endif
/* Include files */
#include <openssl/bio.h>
#include <openssl/x509.h>
/* Macros, structures and function prototypes */
/* BEGIN ERROR CODES */
The BEGINERRORCODES sequence is used by the error code generation
script as the point to place new error codes. Any text after this point
will be overwritten when makeerrors is run. The closing #endif etc.
will be automatically added by the script.
The generated C error code file xxx_err.c will load the header files
<stdio.h>, <openssl/err.h> and <openssl/xxx.h> so the header file must
load any additional header files containing any definitions it uses.

USING ERROR CODES IN EXTERNAL LIBRARIES

It is also possible to use OpenSSL's error code scheme in external
libraries. The library needs to load its own codes and call the OpenSSL
error code insertion script mkerr.pl explicitly to add codes to the
header file and generate the C error code file. This will normally be
done if the external library needs to generate new ASN.1 structures but
it can also be used to add more general purpose error code handling.

INTERNALS

The error queues are stored in a hash table with one ERR_STATE entry for
each PID. ERR_get_state() returns the current thread's ERR_STATE. An
ERR_STATE can hold up to ERR_NUM_ERRORS error codes. When more error
codes are added, the old ones are overwritten, on the assumption that the
most recent errors are most important.
Error strings are also stored in a hash table. The hash tables can be
obtained by calling ERR_get_err_state_table() and ERR_get_string_table().

SYNOPSIS

DESCRIPTION

The error code returned by ERR_get_error() consists of a library
number, function code and reason code. ERR_GET_LIB(), ERR_GET_FUNC()
and ERR_GET_REASON() can be used to extract these.
The library number and function code describe where the error occurred,
the reason code is the information about what went wrong.
Each sub-library of OpenSSL has a unique library number; function and
reason codes are unique within each sub-library. Note that different
libraries may use the same value to signal different functions and
reasons.
ERR_R_... reason codes such as ERR_R_MALLOC_FAILURE are globally
unique. However, when checking for sub-library specific reason codes,
be sure to also compare the library number.
ERR_GET_LIB(), ERR_GET_FUNC() and ERR_GET_REASON() are macros.